Transmission



Feb. 12, 1963 .1. D. LINDSAY TRANSMISSION 8 Sheets-Sheet 1 OriginalFiled Nov. 28, 1958 INVENTOR. JOHN D. ,Dspy

197' 70K/WE Y J. D. LINDSAY Feb. 12, 1963 TRANSMISSION 8 Sheets-Sheet 2Original Filed Nov. 28, 1958 /VVENTOR. JOHN D, /A/Dsy-y Feb. 12, 1963Original Filed Nov. 28. 1958 J. D. LlNDSAY TRANSMISSION 8 Sheets-SheetI5 gpl IN VEN T 0R. JOHN D. fm/am) Feb. 12, 1963 J. D. LINDSAY 3,077,253

TRANSMISSION Original Filed Nov. 28, 1958 8 Sheets-Sheet 4 Feb. 12, 1963J. D. LINDSAY 3,077,253

TRANSMISSION Original Filed Nov. 28, 1958 8 Sheets-Sheet 5 PAPA/#V6PAA/E IN VEN T OR.

g. .0e-5455 JOHA/ D. LM/Dfy Feb. 12, 1963 J. D. LINDSAY 3,077,253

TRANSMISSION Original Filed Nov. 28, 1958 8 Sheets-Sheet 6 THROTTLE01959/9760 VQU/E ,moz/Ame 1N VENTOR.

JOHN D, /q/DJM/ Feb. 12, 1963 J. D. LINDSAY TRANSMISSION Original FiledNov. 28, 1958 PLU/0 COI/#UNG VENT 8 Sheets-Sheet 'T INVENTOR. J0 HA/ D.wos/'9V ATTOQNEY Feb. 12, 1963 J. D. LINDSAY 3,077,253

` TRANSMISSION Original Filed Nov. 28, 1958 8 Sheets-Sheet 8 IMM/6ACCU/#060701? @OWP/VOR r/-f/Ra spira anexa-R INVENTOR. Jol-IN D. LM/osAy@a PC autres Patented heb. l2, ldd? 3,077,253 TRANSMISSION .lohn D.Lindsay, Birmingham, Mich., assigner to General Motors Corporation,Detroit, Mich., a corporation of Delaware @riginal application Nov. 28,1953, Ser, No. 777,112. Divided and this application dan. 1S, 196i),Ser. No. 2,944

Claims. (Cl. M42- 35) This is a division of my application Serial Number777,112, filed November 28, 1958.

This invention relates to transmissions of the type in which a hydraulictorque transmitting device drives change-speed gearing which drives anoutput shaft at a plurality of forward speed ratios, and in reverse. Itrelates to novel features of construction and arrangement of thechange-speed gear; to novel features of the connection between thechange-speed gear and the hydrodynamic torque transmitting device; andto novel features of the hydraulic system for controlling thetransmission.

In particular it relates to a clutch for establishing drive and to animproved timing device for controlling the rate of establishment oftorque in the clutch. It also relates to a fluid coupling or fluidclutch for establishing drive and to improved means for controlling theiilling and emptying of the fluid clutch and thus controlling theestablishment of torque.

In the drawings:

FIG. l is one-half of a schematic, substantially symmetricallongitudinal section showing the functional relationship of the elementsof a transmission embodying one form of the invention;

FIG. 2 is a diagram corresponding to FIG. 1 showing the change-speedwhich forms part of the transmission in lirst gear or low speed drive.in this and in FIGS. 3, 4 and 5, dotted lines indicate parts which arenot active in the transmission of torque from the hydrodynamic torquetransmitting device to the output shaft;

FlG. 3 is a diagram corresponding to FIG. 2 of the change-speed gearingin second gear or intermediate speed;

HG. t shows the gearing in third speed or direct drive; and

FlG. 5 shows the gearing in reverse;

PEG. 6 is one-half of a substantially symmetrical longitudinal sectionof the actual construction of that part of one form of transmissionembodying the invention which includes the huid clutch and frictionclutch;

FIGS. 7, 7A, 7B and 7C, when put together in numerical order from leftto right, collectively form a functional diagram of one form ofhydraulic system for controlling the transmission shown in FGS. l to 6,with the control set for third speed at above three-quarters throttleopening in the direct drive range in which the gearing can shiftautomatically among first, second and third speeds.

Referring to FIG. l the transmission input or driving shaft itl, whichmay be the crankshaft of the usual internal combustion engine, drives ahydrodynamic torque transmitting device l2 which in turn driveschange-speed gearing i4 which drives an output shaft le which may be thepropeller shaft of a conventional automobile. The hydrodynamic torquetransmitting device may be, for example, a torque converter as disclosedin British Patent 776,599, published March 20, i957, the disclosure ofwhich is incorporated herein by reference. in this example the torqueconverter has an impeller 20 driven by the engine shaft lil, a firstturbine T1 and a second turbine T2, through which the torque transferfluid is successively circulated, and a reaction element, stator orguide wheel 2.2, the blade angles of which may be adjusted `by anysuitable mechanism 2d, and which is connected to the frame of thetransmission by a one-way brake 2e which permits the stator to rotateforward but prevents it rotating backward as is known in the art. Thefirst turbine drives the input or ring gear 23 of a planetary gear sethaving planet gears 3b mounted on a carrier 32, and having a reactionsun gear Se? which is connected to the frame of a transmission by aone-way brake 36 which permits the sun gear to rotate forward butprevents it rotating backward as is known. The second turbine T2 isconnected through the carrier 3?; to the torque converter output: shaft38 Which forms the input or driving shaft for the gearing 11i. Thearrangement is such that the torque converter l2 transmits torque to theconverter output shaft 38 at a ratio in respect to the torque on theinput shaft ifi, which ratio varies with the load on the output shaft3S. That is, when the shaft 33 is stationary or rotating at low speedwhich indicates high load, the torque ratio between shaft 33 and shaftitl is high and may be of the order of threeto-one, whereas when thespeed of the shaft 38 approaches the speed of the shaft llt? due to adecrease in load on the shaft 38, the torque ratio is near unity.

Shaft 33 is connected to a housing il which contains a fluid couplingincluding a turbine lli connected to the output shaft la and an impellerconnected by a hollow shaft El?, to a sun gear The housing and thecoupling may be selectively filled with oil or emptied to maize thecoupling effective or ineffective as will be explained. The housing Silis connected to the sun gear by a one-way clutch t5 to drive the sungear forward, but permit the sun gear to overrun or rotate forwardfaster than th housing 4d. The housing 4d may be also connected to thesun gear by an anti-overrun clutch 4S which may be engaged by ahydraulic cylinder Sti to prevent the sun gear from overrunning. Thepurpose of this arrangement is to use the one-way clutch de to transmitthe heavy driving torque from the torque converter to the sun gear anduse the light clutch d to prevent free wheeling when the input to thegearing is through the sun gear, as it is in low forward speed and inreverse, and to let the sun gear 54 rotate forward faster than thehousing Il@ when the input to the gearing is not through the sun gear54. Preferably the clutch 4S is small and capable of transmitting only alight torque, much less than the torque required to drive the carthrough the one-way clutch e5.

The input sun gear 5ft is part of a front planetary gear set whichincludes a ring gear S6 connected by a flange 58 to the output shaft i6,and includes planet gears 63- meshing with the sun gear 54 and ring gear56 and mounted on a carrier 62 which is connected by a drum 65 to thering gear dit of a second or rear planetary gear set. The rear gear setincludes a reaction sun gear 7d and planet gears 72 meshing with thering gear 68 and sun gear 79 and mounted on a carrier 74 which isconnected to the flange 53 attached to the output shaft 151. The drum5d, front carrier `o2 and the rear ring gear de may be held fast toestablish reverse drive by friction member '7d which can be grounded bya cylinder 73. This friction device in this particular usage frequentlyor usually has been called a reverse clutch by engineers andmanufacturers, but has been called a brake by others. This has beenconfusing to engineers who have been confining the term brake tosomethinU that stops the car and have been using the term clutch torefer to something that drives it. In attempting to use a generic termwhich will not conflict with either usage, I use the generic termfriction torque-establishing device to refer both to friction clutchesand 'to friction brakes.

Alternatively, the drum 66, carrier 62 and ring gear 68 may be connectedto the fluid coupling housing 40 and to the input shaft 38 by a directdrive clutch Si? which may be set by a hydraulic cylinder S2. The rearreaction sun gear 70 is connected by a hollow shaft S4 through a onewaytorque-establishing device 86 to a forward reaction frictiontorque-establishing device 88 which may be set by normes a hydrauliccylinder 9d. rfhis provides reaction torque for forward drive, as willbe explained. Free-Wheeling may be prevented by an over-run frictiontorque-establishing device connected to the shaft 84, and settable byany suitable hydraulic cylinder 9d.

Any suitable oil pump such as front pump 96 may be driven by the engineshaft i to provide a source of oil under pressure in response torotation of the engine, for operating the controls of the transmission.Another oil pump 93 called the rear pump is driven by the output shaftTtto provide a source of oil under pressure responsive to forwardmovement of the car. A low speed governor valve ft and a high speedgovernor valve 192 may also be driven by an output shaft te.

Referring to PEG. 2, to establish low or first speed drive between thetorque converter output shaft 33 and the final drive shaft l5, theoverrun friction torque-establishing device t3 is set, the forwardreaction friction torqueestablishing device 83 is set, the overrunfriction torqueestablishing device 92 is set, the direct drive frictiontorque-establishing device 8d and the reverse frictiontorqueestablishing device 76 are released, and the fluid coupling 2P-fili is emptied. The input shaft 38, through casing dit, one-way clutchdo and shaft 52 drives the front input sun gear 54 at a speed, withrelation to the speed of the engine shaft 1t), that is determined by thetorque converter f2. initial resistance to movement of the car holds theshaft f6 stationary which temporarily holds the front ring gear- 56stationary to act as a reaction gear for the front planetary gear set.This causes the front carrier 62 to exert forward torque on the rearring gear 65 and this exerts reverse torque on the sun gear 7d andforward torque on the carrier 7d and output shaft 16. Because theone-way clutch Se and the forward reaction friction torque-establishingdevice Sti prevent reverse rotation of the sun gear 70, this drives theoutput shaft f6 forward at a reduced speed which takes advantage of thespeed reductions effected by both the front and rear planetary gearsets. The overrun friction torque-establishing devices 4b and 92 preventthe car from free wheeling when the car tends to run faster than theengine would drive it.

Referring to FIG. 3, to set the gearing in second or intermediate speed,the overrun friction torque-establishing device d3 is released, fluidcoupling i2-i45- is emptied, the direct drive frictiontorque-establishing device Si) is set, the reverse frictiontorque-establishing device '76 is released, the overrun frictiontorque-estabiishing device 92 is set, andthe forward reaction frictiontorque-establishing device 8d is set. The gearing input shaft 3S nowdrives the rear ring gear of; through the casing of the uid coupling 49,the direct drive friction torque-establishing device ttt? and the drum66. The rear reaction sun gear 70 is held against reverse rotation bythe torque-establishing devices Se and 8d as in low speed and thisdrives the carrier 74 and output shaft f6 at a speed reductiondetermined by the ratio of the rear planetary gear set 6%- 72-7tl,alone. The one-way clutch in lets the front sun gear 54 run faster thanthe casing 49 and carrier 62 and this lets the front planetary gearsetd-eti-Ed idle. Freewheeling on overrun is prevented by the frictiontorque-establishing device 92.

Referring to FiG. 4, provision is made for a third speed which is adirect drive with the input torque divided between mechanical drive andfluid drive. To establish third speed the fluid coupling i2- dll isfilled, theoverrun friction torque-establishing device `d is released,the direct drive friction torque-establishing device Sii is engaged, thereverse friction torque-establishing device 76 is released, the overrunfriction torque-establishing device 92 is released, and the forwardreaction friction torqueestablishing device 8S remains engaged butinactive, allowing sun gear 7@ to turn forward, because of one-waydevice 86.

This drives connection to the input the input member of the frontplanetary gear set.

the front carrier 62 by direct mechanical shaft 33, the carrier nowbeing This 5. fo ward torque on both the ring gear 56 5ft, which latterthrough fluid coupling ts torque on the output shaft i6. Thus gearsetimpresses and the sun gear impresses the output shaft o is drivensubstantially at the speed of the input shaft 3%-, and the torque fromthe shaft 38 is divided by the front gearset into a mechanical componentthrough ring gear 56 and a hydraulic component through sun gear 34. Theratio of the components is established by the ratio of the number ofteeth in the ring gear to the number of teeth in the sun gear, theproportion through the sun gear being the smaller, as is known. Sincethe ring gear 5o and the turbine de necessarily turn at the speed of theshaft f6, and the sun gear 5d runs faster than the ring gear 5o, the sungear drives the irnpeller ft2 faster than the speed of the casing dit,as permitted by the one-way clutch do.

Referring to FiG. 5 for reverse drive the overrun frictiontorque-establishing device d8, the direct drive frictiontorque-establishing device Sti, the overrun friction torqueestablishingdevice 92 and the forward reaction frictiontorque-establishing devicetid are all released, the fluid coupling Q-d is emptied, and reversefriction torqueestablishing device 7o is set. The torque converteroutput shaft 313 now drives the shaft 52 through the one-way clutch d6,and because the friction torque-establishing device 76 holds the carrier62 the sun gear 5d drives the ring gear Se backward which drives theoutput shaft 1.6 backward at low speed ratio.

l il

Structure FIG. 6 shows one form of actual structure of the fluidcoupling rtf-2 and the clutch tit) with their associated parts in atransmission embodying the invention.

As shown at the left of FIG. 6 the rear or right end of 5 the torqueconverter output shaft 38 rotates in a stationary casing EItZ-Eld-lt andis keyed or splined to a front radial iange 1'7" ti formed integral withan outer cylindrical drum 172 which is keyed to a rear radial fiange.f7-t as by teeth E75 shown at the bottom of the drawing. The fiangesand drum together constitute the uid coupling casing lb which is attimes to be filled with oil under pressure. In order to contain the oilin the casing the front frange f7@ has a rotating seal connection 1176with a sleeve forming part of the stationary wall td and the rear flange'E74 is sealed to the drum i172 by a gasket 73, shown at the bottom ofthe drawing, and has a rotating sealing connection fd@ with a flange ona stationary wall 152, forming part of the casing flo.

The front flange f7@ contains control valves, which will be described,for admitting and releasing oil from the casing 4t.

As shown in the lower half of the drawing, the rear flange f7@ isriveted to the inner race 184 of the oneway clutch i6 whose rollers orsprags fdd engage a cam ring or outer race is@ of known form riveted tothe irnpeller i2 of the fluid coupling i2-tid. The impeller is splinedat f3@ to the gearing input shaft 52. The one-way clutch to is arrangedso that forward rotation of the casing it? drives the impeller, but theimpeller can rotate forwardly faster than the casing 4t). The impellerd2 and outer race 13S are also splined to the driving plate 192 of theover-run clutch d6 which may be set by the piston i942 when oil underpressure is admitted to the cylinder 5d. This locks the inipeller to thecasing di) so that the car can drive the engine which thus serves tobrake the car.

The gearing input shaft 52 is keyed at its rear or right end, as FlG. 6is seen, to the front input sun gear 54 which meshes with the planets6i? journalled on spindles i196 forming part of the carrier 62 andsupported in a rear cheek plate 195 and a front cheek plate 2% keyed tothe rurn do and splined to the driven plates 202 of the direct driveclutch The driving plates 29d of the clutch Sti are splined to a clutchhub 2de splined to the rear end of a holiow shaft 2648, the front end ofwhich is splined to the rear flange 17d of the fluid coupling casing 4t)so that the driving plates 204 are driven by the torque converter outputshaft 33. The main clutch Si) is normally disengaged by a release spring219 which constantly urges to the left e clutch apply piston 212 whichcan be moved to the right to engage the clutch by the pressure of oiladmitted to th=l cylinder 82 through a control passage 2.14l near thecenter of the cylinder, formed integral with the drum 66. In order toinsure release or the clutch and prevent the building up of ccntrifugalpressure in the chamber 82 when the pressure in the passage 214 isreleased, the piston is provided near its rim with the release passage216 and a centrifugal dump valve 218 which may be constructed as shownin the U.S. patent to Harold Fischer 2,740,512, the disclosure of whichis included herein by reference.

As shown in FIG. 6 the turbine 44 of the fluid coupling i2- 44 isconnected to the output shaft 16. For mechanical convenience thisconnection is formed by a shaft d secured at its front end to theturbine 44 by a spline 252, and splined at its rear end to the interiorof a ring 254, the outside of which is splined to the front cheek plate244 of the carrier 74 and so is connected to the output shaft i6. Theplanet gears 72 mesh with the reaction sun gear 7 d which is formedintegral with a short hollow shaft 256 rotatably supported on the outputshaft 16 in any suitable manner.

As shown in the lower part of FIG. 6 the front ange 171i of the fluidcoupling housing 40 has a bore 324 which can till the casing 4t) andfluid coupling t9-42 through an opening 326 from' an oil supply passageor gland 328 in the stationary wall 31.14. The bore 324 contains aninlet valve 33d urged closed by a spring 332 to prevent communicationbetween the gland 323 and the interior of the tiuid coupling. Wheneverthe fluid coupling is to be filled, oil under pressure is supplied bythe control system to the gland 328, the pressure opens the valveagainst the force of spring 332 and oil ows into the coupling. T hespring 332 has suilicient force to hold the valve closed againstcentrifugal force.

As shown in the upper half of FG. 6 the front flange Itll also has anoutlet bore 3d@ leading from a vent passage 342 of the fluid coupling tothe space 344 surrounding the fluid coupling casing di? whichcommunicates with the usual sump forming part of the casing 116, whichis substantially at atmospheric pressure, as is known. The outlet bore341') contains a fixed valve sleeve 346 which guides a reciprocal valveassembly, including valve cap 348 mounted on a stem 35) integral with apiston 352 slidable in the sleeve. Mm the valve outward, that is upwardas HG. 6 is seen so that the valve cap vents the coupling to the space3445 through the passage 35dmatching the vent opening 342. The spacebetween the sleeve 34.16 and the piston 352 forms a valve closingchamber 356 which is in communication with the passage 357 in the flangeiti/'tl which in turn is in communication with a gland 35d in the wall114 to which oil under pressure may be admitted from the control systemto urge the piston 352 inwardly against the spring to close the exhaustvalve. Whenever the luid coupling is to be filled oil under pressure issupplied from the control system to the gland 35S to close the exhaustvalve 34S and oil under pressure is admitted to the inlet passage 326 toopen the inlet valve 33@ and supply uid to fill the coupling, as will beexplained below in the discussion of the control system. In order toempty the fluid coupling, the control system cuts ofi fluid from thepassages 3:25 and 35S. The spring 352 then opens the vent valve and theluid is drained from the coupling by centrifugal force. Preferably anumber of inlet valves and exhaust valves like those shown in PEG. 6 aredisposed about the circumference of the flange 179 in order to. efiect.rapid filling and emptying of the coupling.

A spring .ses normally urges Control System As more fully disclosed inmy parent application, Serial Number 777,112, in general the controlsystemI includes the front and rear pumps $6 and 98 which constitutereservoirs or sources of control oil under pressure whenever the engineis running or the car is moving forward; a manually operated selectorvalve which determines whether the transmission will drive the carforward or backward, and if forward, whether it will be held in trstspeed, or will be permitted to upshift automatically to second speedonly or to second and third speeds; a pump pressure regulator whichnormally maintains a constant pump pressure out which can be inliuencedby various modiers or modulators to change the pressure as may berequired by different driving conditions; a clutch shift valve forselectively `setting or releasing the direct drive clutch 43; a duidcoupling shift valve for selectively filling and emptying the fluidcoupling; a stator control valve for placing the stator blades in eitherhigh or low angle; and various relay, blocker or inhibitor valves whichpermit or prevent operation of other elements of the control system inaccordance with the requirements of automatic and manual gear ratioselection. The shift valves are urged to shift up by governor-generatedpressure as the speed of the car increases and are urged to shift downby pressure representing torque or power demand as indicated by throttleopening.

Referring to FlGS. 7, 7A, 7B, 7C, the front pump 96 takes in oil from asump 39d, customarily formed by a portion of the transmission casing116, and discharges oil under pressure to a main line 499. The pressureof the main line urges to the left in FIG. 7 the Valve stem 401 of apressure regulator valve generally designated by 462, against the forceof a return spring 403 in a pressure chamber 49311. As disclosed in theHerndon Patent 2,763,162 this arrangement maintains a constant pressurein the main line 496 when there is a constant pressure or no pressure inthe cham-ber 463er, but the pressure of the main line can be changed bychanging t'ne pressure in the chamber M3351.

As shown in FIGS. 2-5 the direct drive clutch Sil is engaged both insecond speed (FiG. 3) and third speed (FIG. 4) but in no other speed,and the tluid coupling t2- 44 is filled to transmit torque only in thirdspeed.

Referring to FlGS. 7, 7A, 7B, 7C, in order to drive the car in directdrive range in which first, second and third gear is selectedautomatically in accordance with speed and torque conditions, the manualvalve stem Hi8 is placed in the D for drive position, as shown in FIG.7A. This vents the intermediate range control line 442 throughintermediate .port 422 and vent port 4l2 of the manual valve, and sovents the closing chamber 706 of the 3rd speed blocker valve '792 (FIG.7C), permitting this valve to be opened by the spring 764 so that thefluid coupling 42, 44 can be lled as will be explained. Venting theintermediate control line 442 also vents the line 44d and consequentlyvents the overrun friction torqueestablishing device apply chamber l torelease the overrun friction torque-establishing device 83. Otherwisethe controls are now conditioned for drive in iirst and second speed.The throttle is closed and low gear drive is established by pressurizingthe forward reaction friction torque-establishing chamber 39 throughlines 434 and 436, (FIGS. 7A, 7C), leading from open drive port 42h onthe selector valve 466 (FIG. 7A) connected to main line dei?. When thethrottle is opened the transmission will start in rst gear and willshift up into second gear as car speed increases as more fully describedin the parent application S.N. 77 7,1 l2.

It is noted that when the transmission control is set for eitherintermediate or direct drive `range the forward reaction frictiontorque-establishing device apply chamber 96 is pressurized to establishlow gear drive and the direct clutch chamber 82 is pressurized by thel-2 shi valve 57th automatically in response to driving codition Whenthe -fluid coupling i2-ifi is iilled the third speed drive is picked upwithout releasing the low speed reaction friction torque-establishingdevice 3% the su gear 7? overruns the friction torgueestabiishing device83 because of the one-way clutch Se. in order to efect a smoothtransition from iirst gear to second gear drive the direct clutchchamber d2 is filled gradually to engage the clutch 24.3 gently. Thismay be accomplished by any suitable timing or cushioning device. lprefer to use the accumulator and timing valve arrangement shown in FIG.7C. This includes an expansible chamber' 72b closed by a piston 722urged to the right by a spring 724 and urged to the left by thedifference in pressure between lines 51d and 2M. The piston has a slowhow passage 726 which always connects lines 5141 and Zilli, and a fastow passage 723 normally closed by a ball check valve 73d, which can bepushed ot its seat by a pin 732 to open the fast flow passage.

Whenever the direct clutch apply line Sid is rst pressurized the directclutch chamber 32 and the chamber 720 have been vented and consequentlythese spaces are at low pressure. The line pressure in the passage S34pushes the piston 7122 to the left so that pin 732 opens the fast owpassage 72S and oil flows rapidly through the passage 72S to till thereduced volume of the chamber 72? and the clutch chamber n2. It isintended that this space will be filled quickly at suicient pressure totake up clearance between the clutch plates 262 and 29d of the clutchdi?. When the clearance is taken up the clutch chamber E2 stopsexpanding so that the pressure in the clutch chamber S2 and space 729will tend to increase suddenly, which if permitted would cause theclutch to grab and give a rough shift. This is prevented by theexpansion of the chamber 72d. As soon as the slack is taken up theincrease of pressure in chamber '72d moves the piston 722 away from thepin 73.2, seating the ball and closing the fast-how passage 729. Afterthat oil flows slowly thru the slow flow passage 726 and graduallybuilds up pressure in the clutch chamber 82 and in the expandingaccumulator chamber 72b. Consecuently full torque capacity of the clutchd@ is established gradually. This makes a gentle transition from firstspeed drive to second speed drive.

When transmission is shifting down from second speed to iirst speed theline Sid is Vented and the check valve 73h opens to permit rapid releaseof the clutch 39. This is desirable to give the engine time to speed upto the higher speed required for iirst gear drive, as is known. Sinceiirst s eed is established as soon as the one-way clutch d6 locks up,this arrangement provides a smooth downshift.

After the speed and torque conditions establish second gear drive asdescribed, further increase in car speed establishes third speed drivethrough the action of a 2-3 shift valve shown in FiG. 7A. This shiftvalve is held closed, or downshitted, when there is no pressure in thecontrol system, by a light spring 575, in order to insure the valvebeing closed when the system is started, at which time there may be zerothrottle pressure. As soon as the l-2 shift valve 57@ has opened orupshifted, the main line ed@ is connected to a supply passage 742leading to the .2-3 shift valve 746. At low speed or at relatively hightorque demand the valve stem 7134 of the 2-3 shift valve 74d is heldclosed, as shown in FlG. 7A by the spring 375 and/or TV pressure inclosing or downshift chambers 746 and 748. With the valve closed, theline 7552 is blocked by the valve stern 74e and a third speed controlline 75d is vented at exhaust port 752. The valve stem 74dis urged toopen or upshift by upshift chambers 75d and 756 supplied with governorpressure from the line 62d. At some given throttle opening the governorpressure at some predetermined car speed is sufficient to move the valvestern 7de up against TV pressure in chambers 746 and 748 to close thevent 752 connect main line pressure from 7/2 to the third speed controlline 75d. This upshift always occurs after upshift of the l-Z valve 57dso that the line 742 is supplied with main line pressure. When the valve75rd upshifts, the third speed control line 75d is pressurized, andsince third speed blocker valve 7 d2 is open, this pressurizes the line7b@ and pressurizes closing chamber 35d of the uid coupling vent valveEdd (FIGS. 6, 7B). This closes the vent valve. The line 7d@ also opensthe iuid coupling relay valve oil@ (FiG. 7) by pressurizing the chamber69S and this connects main line dit? to the iiuid coupling iillingpassage 32S (FIGS. 6 and 7). This lills the fluid coupling to establishthird speed or direct split torque drive as described `in connectionwith FiG. 4. The forward reaction friction torque-establishing device 38remains set but the one-way clutch 86 freewheels as permitted by theoverrun friction torqueestablishing de vice 92.

increase of throttle opening at a given speed or decrease of speed at agiven throttle opening will cause the 2-3 shift valve 74d to downshiftto establish second speed drive by venting the third speed control line756`1 at exhaust port 752 which vents the vent valve closing cylinder356 permitting the lluid coupling vent valve 3dS to be opened by thespring 353 (HG. 6). Venting of the line 7% also permits the fluidcoupling relay valve 69@ to be closed by its spring 6%2 to cut olfsupply of oil from the main line 49? to the liuid coupling fillingpassage 323 (FGS. 6, 7).

I claim:

l. A power transmission comprising in combination, a frictiontorque-establishing device for establishing a driving connection betweendriving and driven members; an engaging chamber for receiving iluidunder pressure to establish in the torque-establishing device torquemeasured by the pressure in the engaging chamber; and means forcontrolling the rate of establishment of torq ze in thetorque-establishing device including a control chamber connected to theengaging chamber, a fluid pressure supply conduit, a constantly openslow ow passage and a fast flow passage both connected to conduct liuidfrom the conduit to `the control chamber, means constantly tending toclose the fast-How passage, and means responsive to initial existence ofpressure in the supply conduit for opening the fast-fiow passage, saidclosing means being responsive to excess of pressure in the controlcharnber over pressure in the supply conduit for opening the fast-howpassage.

2. A power transmission comprising in combination, a frictiontorque-establishing device for establishing a driving connection betweendriving and driven members; an engaging chamber for receiving huid underpressure to establish in the torque-establishing device torque measuredby the pressure in the engaging chamber; and means for controlling therate of establishment of torque in the torque-establishing deviceincluding a control chamber connected to the engaging chamber, a fluidpressure supply conduit, a constantly open slow-dow passage and afast-flow passage both connected between the conduit and the controlchamber, means constantly tending to close the fast-now passage, meansresponsive to initial existence of pressure in the supply conduit foropening the fast-flow passage and means subsequently responsive to apredetermined difference in pressure between the control charnber andthe supply conduit for closing the fastflow passage, said closing meansbeing responsive to excess of pressure in the control er over pressurein the supply conduit for opening the fast-flow passage.

3. A power transmission comprising in combination, a frictiontorque-establishing device for establishing a driving connection betweendriving and driven members; an engaging chamber for receiving fluidunder pressure to establish in the torque-establishing device torquemeasured by the pressure in the engaging charnber; and means Iforcontrolling the rate of establishment of torque in thetorque-establishing device including an expansible and contractiblecontrol chamber connected to the engaging chamber, a uid pressure supplyconduit, means responsive to initial existence of pressure in theconduit for reducing the volume of the control chamber, means responsiveto a predetermined reduction of volume of the control chamber forestablishing communication between the conduit and the chambers at apredetermined rate of How and means subsequently responsive to apredetermined difference of pressure between the chambers and theconduit for reducing the rate of ow into the control chamber to expandthe control chamber at a slow rate.

4. A power transmission comprising in combination, a frictiontorque-establishing device for establishing a driving connection betweendriving and driven members; an engaging chamber for receiving fluidunder pressure to establish in the torque-establishing device torquemeasured by the pressure in the engaging chamber; and means 4forcontrolling the rate of establishment of torque in thetorque-establishing device including an expansible and contractiblecontrol chamber connected to the engaging chamber, a tluid pressuresupply conduit, a movable piston forming one Wall of the control chamberand means responsive to initial existence of pressure in the conduit forreducing the volume of the control chamber, means responsive to apredetermined movement of the piston for establishing communicationbetween the conduit and the chambers at a predetermined rate of flow andmeans subsequently responsive to a predetermined dilerence of pressurebetween the chambers and the conduit for reducing the rate of flow andthereby expanding the control chamber at a slow rate.

5. A power transmission comprising in combination, a Africtiontorque-establishing device for establishing a driving connection betweendriving and driven members; an engaging chamber for receiving uid underpressure to establish in the torque-establishing device torque measuredby the pressure in the engaging chamber; and means for controlling therate of establishment of torque in the torque-establishing deviceincluding a control cham- -ber including a movable piston the positionof which determines the volume of the control chamber, a springconstantly urging the piston to increase the volume of the chamber, ailuid pressure supply conduit, the piston being responsive to pressurein the conduit to tend to move in the direction decreasing the volume ofthe control chamber, a fast ow passage and a slow flow passage throughsaid piston connecting said conduit and said control chamber, `a valvenormally closing the fast ow passage, and means responsive to apredetermined. movement of the piston due to pressure in the conduit foropening the valve to increase the pressure in the control chamber, saidcontrolling means being responsive to a predetermined 4diierence ofpressure between the conduit and the control chamber for moving thepiston in the direction to increase the volume of the control chamber toclose the valve.

References Cited in the le of this patent UNITED STATES PATENTS 918,652Bryan Apr. 20, 1909 2,702,618 Baker et al. Feb. 22, 1955 2,721,640 DeFeo et al. Oct. 25, 1955 2,785,583 Kelbel Mar. 19, 1957 2,861,589Ostwald Nov. 25, 1958 2,886,065 Hershman May l2, 1959

1. A POWER TRANSMISSION COMPRISING IN COMBINATION, A FRICTIONTORQUE-ESTABLISHING DEVICE FOR ESTABLISHING A DRIVING CONNECTION BETWEENDRIVING AND DRIVEN MEMBERS; AN ENGAGING CHAMBER FOR RECEIVING FLUIDUNDER PRESSURE TO ESTABLISH IN THE TORQUE-ESTABLISHING DEVICE TORQUEMEASURED BY THE PRESSURE IN THE ENGAGING CHAMBER; AND MEANS FORCONTROLLING THE RATE OF ESTABLISHMENT OF TORQUE IN THETORQUE-ESTABLISHING DEVICE INCLUDING A CONTROL CHAMBER CONNECTED TO THEENGAGING CHAMBER, A FLUID PRESSURE SUPPLY CONDUIT, A CONSTANTLY OPENSLOW FLOW PASSAGE AND A FAST FLOW PASSAGE BOTH CONNECTED TO CONDUCTFLUID FROM THE CONDUIT TO THE CONTROL CHAMBER, MEANS CONSTANTLY TENDINGTO CLOSE THE FAST-FLOW PASSAGE, AND MEANS RESPONSIVE TO INITIALEXISTENCE OF PRESSURE IN THE SUPPLY CONDUIT FOR OPENING THE FAST-FLOWPASSAGE, SAID CLOSING MEANS BEING RESPONSIVE TO EXCESS OF PRESSURE INTHE CONTROL CHAMBER OVER PRESSURE IN THE SUPPLY CONDUIT FOR OPENING THEFAST-FLOW PASSAGE.